Method and apparatus for configuring demodulation reference signal position in wireless cellular communication system

ABSTRACT

The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. A method by a terminal in a wireless communication system is provided. The method includes identifying a slot type of a terminal from a first slot type and a second slot type, determining a position of a demodulation reference signal (DMRS) based on the slot type, and receiving the DMRS based on the position from a base station.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based on and claims priority under 35 U.S.C. §119(a) of a Korean patent application number 10-2017-0053659, filed onApr. 26, 2017, in the Korean Intellectual Property Office, thedisclosure of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The disclosure relates to a wireless communication system. Moreparticularly, the present disclosure relates to a method and anapparatus for configuring and indicating a position of a demodulationreference signal (DMRS).

BACKGROUND

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a ‘Beyond 4G Network’ or a‘Post LTE System’. The 5G communication system is considered to beimplemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, soas to accomplish higher data rates. To decrease propagation loss of theradio waves and increase the transmission distance, the beamforming,massive multiple-input multiple-output (MIMO), Full Dimensional MIMO(FD-MIMO), array antenna, an analog beam forming, large scale antennatechniques are discussed in 5G communication systems. In addition, in 5Gcommunication systems, development for system network improvement isunder way based on advanced small cells, cloud Radio Access Networks(RANs), ultra-dense networks, device-to-device (D2D) communication,wireless backhaul, moving network, cooperative communication,Coordinated Multi-Points (CoMP), reception-end interference cancellationand the like. In the 5G system, Hybrid FSK and QAM Modulation (FQAM) andsliding window superposition coding (SWSC) as an advanced codingmodulation (ACM), and filter bank multi carrier (FBMC), non-orthogonalmultiple access (NOMA), and sparse code multiple access (SCMA) as anadvanced access technology have been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof Things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The Internet ofEverything (IoE), which is a combination of the IoT technology and theBig Data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “Security technology” have been demanded forIoT implementation, a sensor network, a Machine-to-Machine (M2M)communication, Machine Type Communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing Information Technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, Machine Type Communication (MTC), andMachine-to-Machine (M2M) communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud RadioAccess Network (RAN) as the above-described Big Data processingtechnology may also be considered to be as an example of convergencebetween the 5G technology and the IoT technology.

On the other hand, there has been a need for a method for effectivelytransmitting a demodulation reference signal (DMRS) in various slotstructures in the 5G wireless communication system.

The above information is presented as background information only toassist with an understanding of the disclosure. No determination hasbeen made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

In a wireless communication system, in order for a terminal to estimatea channel, a base station (BS) should transmit a reference signal. Theterminal may perform channel estimation using the reference signal, andmay demodulate a received signal. Further, the terminal may grasp thechannel state, and may use this to give feedback to the BS. In fifthgeneration (5G) wireless communication, unlike a long term evolution(LTE) system, front-loaded demodulation reference signal (DMRS) has beenconsidered as a method for minimizing latency by shortening timerequired for data demodulation through fast channel estimation. Further,since the 5G wireless communication system supports various slotstructures, there is a need for a method for configuring and indicatinga position of the front-loaded DMRS for this. In this case, the positionof the front-loaded DMRS exerts a great influence on the latency. Incontrast, if the position of the front-loaded DMRS is dynamicallychanged according to circumstances to minimize the latency, it becomesdifficult to manage DMRS interference in a synchronized network.

Aspects of the disclosure are to address at least the above-mentionedproblems and/or disadvantages and to provide at least the advantagesdescribed below. Accordingly, an aspect of the disclosure is to providean effective method for configuring a DMRS position in various slotstructures.

In accordance with an aspect of the disclosure, a method of a terminalis provided. The method includes identifying a slot type of a terminalfrom a first slot type and a second slot type, determining a position ofa DMRS based on the slot type, and receiving the DMRS based on thedetermined position from a base station.

In accordance with another aspect of the disclosure, a terminal isprovided. The terminal includes a transceiver configured to transmit andreceive a signal, and at least one processor configured to identify aslot type of a terminal from a first slot type and a second slot type,determine a position of a demodulation reference signal (DMRS) based onthe slot type and control the transceiver to receive the DMRS based onthe determined position from a base station.

In accordance with another aspect of the disclosure, a method of a BS isprovided. The method includes transmitting a DMRS on a position in timedomain to a terminal, wherein a slot type of the terminal is identifiedfrom a first slot type and a second slot type and the position of theDMRS is determined based on the slot type by the terminal.

In accordance with another aspect of the disclosure, a BS is provided.The BS includes a transceiver configured to transmit and receive asignal, and at least one processor configured to control the transceiverto transmit a DMRS on a position of a DMRS, wherein a slot type of aterminal is identified from a first slot type and a second slot type andthe position of the DMRS is determined based on the slot type by theterminal.

As described above, the disclosure relates to a method and an apparatusfor configuring and indicating a position of a DMRS. As the 5G wirelesscommunication system supports various slot structures, there is a needfor a method for configuring and indicating the position of thefront-loaded DMRS. Through the provided method, the DMRS position can beeffectively configured in various slot structures, and thus efficienttransmission of radio resources becomes possible.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a diagram illustrating a basic structure of a time-frequencydomain that is a radio resource region in which data or a controlchannel is transmitted on a downlink (DL) in a long term evolution(LTE)/LTE-advanced (LTE-A) system according to an embodiment of thedisclosure;

FIG. 2 is a diagram illustrating a basic structure of a time-frequencydomain that is a radio resource region in which data or a controlchannel is transmitted on an uplink (UL) in an LTE/LTE-A systemaccording to an embodiment of the disclosure;

FIG. 3 is a diagram illustrating a radio resource of 1 resource block(RB) that is the minimum unit that can be DL-scheduled in an LTE/LTE-Asystem according to an embodiment of the disclosure;

FIG. 4 is a diagram illustrating DL centric/DL only/UL centric/UL onlystructures as supportable slot structures in a fifth generation (5G) newradio (NR) system according to an embodiment of the disclosure;

FIG. 5 is a diagram illustrating a position of front-load demodulationreference signal (DMRS) if a slot length corresponds to 7 or 14orthogonal frequency division multiplexing (OFDM) symbols according toan embodiment of the disclosure;

FIGS. 6A, 6B, and 6C are diagrams illustrating a position where oneadditional extended/additional DMRS is transmitted in case of 14 OFDMsymbols according to various embodiments of the disclosure;

FIGS. 7A, 7B, and 7C are diagrams illustrating a DMRS pattern accordingto various embodiments of the disclosure;

FIG. 8 is a diagram illustrating a position of front-loaded DMRS if alength of a basic slot is configured to y=6 or y=12 with respect to anextended cyclic prefix (CP) (ECP) in case where a subcarrier interval is60 kHz according to an embodiment of the disclosure;

FIG. 9 is a diagram illustrating a position of a DMRS according to anembodiment of the disclosure;

FIG. 10 is a diagram explaining a method for configuring a DMRS positionby a data starting position indicator according to an embodiment of thedisclosure;

FIG. 11 is a diagram explaining a method for configuring a DMRS positionby control format indicator (CFI) and slot symbol durations according toan embodiment of the disclosure;

FIG. 12 is a diagram illustrating a basic slot structure in which DL andUL exist at the same time according to an embodiment of the disclosure;

FIG. 13 is a block diagram illustrating an internal structure of aterminal according to an embodiment of the disclosure; and

FIG. 14 is a block diagram illustrating an internal structure of a basestation according to an embodiment of the disclosure.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructure.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thedisclosure. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of thedisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of thedisclosure is provided for illustration purpose only and not for thepurpose of limiting the disclosure as defined by the appended claims andtheir equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

A wireless communication system was initially developed for the purposeof providing a voice-oriented service, but has been expanded to, forexample, a broadband wireless communication system that provides ahigh-speed and high-quality packet data service like communicationstandards, such as third generation partnership project (3GPP) highspeed packet access (HSPA), long term evolution (LTE) or evolveduniversal terrestrial radio access (E-UTRA), LTE-advanced (LTE-A), 3GPP2high rate packet data (HRPD), ultra mobile broadband (UMB), and IEEE802.16e. Further, as the 5th generation wireless communication system,fifth generation (5G) or new radio (NR) communication standards havebeen made.

In an LTE/LTE-A system that is a representative example of the broadbandwireless communication systems, a downlink (DL) adopts an orthogonalfrequency division multiplexing (OFDM) scheme, and an uplink (UL) adoptsa single carrier frequency division multiple access (SC-FDMA) scheme.The UL means a radio link in which a terminal (or user equipment (UE))or a mobile station (MS) transmits data or a control signal to a basestation (BS) (or evolved node B (eNB)), and the DL means a radio link inwhich the BS transmits data or a control signal to the terminal.According to the above-described multiple access schemes, data ofrespective users or control information can be discriminated from eachother by performing an allocation and an operation so as to preventtime-frequency resources for carrying the data or control informationfor each user from overlapping each other, that is, to establishorthogonality.

FIG. 1 is a diagram illustrating a basic structure of a time-frequencydomain that is a radio resource region in which data or a controlchannel is transmitted on a DL in an LTE/LTE-A system according to anembodiment of the disclosure.

Referring to FIG. 1, a horizontal axis represents a time domain, and avertical axis represents a frequency domain. In the time domain, theminimum transmission unit is an OFDM symbol, and Nsymb OFDM symbols 102constitute one slot 106, and two slots constitute one subframe 105. Thelength of the slot is 0.5 ms, and the length of the subframe is 1.0 ms.Further, a radio frame 114 is a time domain region that is composed of10 subframes. In the frequency domain, the minimum transmission unit isa subcarrier, and the transmission bandwidth (BW) of the whole system iscomposed of N_(BW) subcarriers 104 in total.

In the time-frequency domain, the basic unit of resources is a resourceelement (RE) 112 that may be expressed by an OFDM symbol index and asubcarrier index. A resource block (RB) (or physical RB (PRB)) 108 isdefined by Nsymb successive OFDM symbols 102 in the time domain andN_(RB) successive subcarriers 110 in the frequency domain. Accordingly,one RB 108 is composed of Nsymb×N_(RB) REs 112. In general, the minimumtransmission unit of data is an RB unit. In an LTE system, Nsymb=7,N_(RB)=12, and N_(BW) and N_(RB) are in proportion to the bandwidth ofthe system transmission band. The data rate is increased in proportionto the number of RBs that are scheduled to the terminal. The LTE systemmay define and operate 6 transmission bandwidths. In the case of an FDDsystem that operates to discriminate between a DL and an UL by means offrequency, the DL transmission bandwidth and the UL transmissionbandwidth may differ from each other. A channel bandwidth presents an RFbandwidth that corresponds to the system transmission bandwidth. Table 1below presents the corresponding relationship between the systemtransmission bandwidth that is defined by the LTE system and the channelbandwidth. For example, the LTE system having a channel bandwidth of 10MHz has the transmission bandwidth that is composed of 50 RBs.

TABLE 1 Channel bandwidth BW_(Channel) [MHz] 1.4 3 5 10 15 20Transmission bandwidth 6 15 25 50 75 100 configuration N_(RB)

FIG. 2 is a diagram illustrating a basic structure of a time-frequencydomain that is a radio resource region in which data or a controlchannel is transmitted on an UL in an LTE/LTE-A system according to anembodiment of the disclosure.

Referring to FIG. 2, a horizontal axis represents a time domain, and avertical axis represents a frequency domain. In the time domain, theminimum transmission unit is a SC-FDMA symbol 202, and N_(symb)ULSC-FDMA symbols may constitute one slot 206. Further, two slotsconstitute one subframe 205. In the frequency domain, the minimumtransmission unit is a subcarrier, and the transmission bandwidth 204 ofthe whole system is composed of N_(BW) subcarriers in total. N_(BW) mayhave a value that is proportion to the system transmission bandwidth.Subcarriers 210 correspond to subcarriers 110 of FIG. 1, and radio frame214 corresponds to radio frame 114 of FIG. 1.

In the time-frequency domain, the basic unit of resources is an RE 212that may be defined by an SC-FDMA symbol index and a subcarrier index.An RB pair 208 is defined by N_(symb)UL successive SC-FDMA symbols inthe time domain and N_(sc)RB successive subcarriers in the frequencydomain. Accordingly, one RB is composed of N_(symb)UL×N_(sc)RB REs. Ingeneral, the minimum transmission unit of data or control information isan RB unit. The PUCCH is mapped onto the frequency domain thatcorresponds to 1 RB, and is transmitted for one subframe.

FIG. 3 is a diagram illustrating a radio resource of 1 RB that is theminimum unit that can be DL-scheduled in an LTE/LTE-A system accordingto an embodiment of the disclosure. On the radio resource illustrated inFIG. 3, different kinds of signals may be transmitted as follows.

1. Cell specific reference signal (RS) (CRS): This is a reference signalperiodically transmitted for all terminals belonging to one cell, andcan be commonly used by a plurality of terminals.

2. Demodulation reference signal (DMRS): This is a reference signaltransmitted for a specific terminal, and is transmitted only in case oftransmitting data to the corresponding terminal. The DMRS may becomposed of 8 DMRS ports in total. In LTE/LTE-A, ports 7 to 14corresponding to DMRS ports, and the ports maintain orthogonality sothat interference does not occur between them using a CDM or FDM.

3. Physical DL shared channel (PDSCH): This is a data channeltransmitted to a DL, and is used by a BS to transmit traffic to aterminal. This is transmitted using an RE whereby a reference signal isnot transmitted in the data region of FIG. 2.

4. Channel status information reference signal (CSI-RS): This is areference signal transmitted for terminals belonging to one cell, and isused to measure the channel state. A plurality of CSI-RSs may betransmitted to one cell.

5. Other channels (physical hybrid automatic repeat request (ARQ)indicator channel (PHICH), physical control format indicator channel(PCFICH), and physical downlink control channel (PDCCH)): They are usedto provide control information that is necessary for a terminal toreceive the PDSCH, or to transmit acknowledgment/non-acknowledgment(ACK/NACK) to operate a hybrid-ARQ (HARQ) for UL data transmission.

In case of the DMRS among the above-described signals, as illustrated inFIG. 3, the position of the DMRS is fixed. However, unlike the LTEsystem, since various slot structures are supported in the 5G wirelesscommunication, and thus the position of the DMRS may not be fixedlyconfigured. More specifically, according to 3GPP RAN1#86bis agreement,the slot of the 5G NR communication system is defined as follows.

-   -   For subcarrier spacing (SCS) of up to 60 kHz with null cyclic        prefix (NCP), y=7 and 14    -   for further study (FFS): whether/which to down select for        certain SCS(s)    -   For SCS of higher than 60 kHz with NCP, y=14

Here, y denotes a slot length represented by the number of OFDM symbols.In the agreement, the slot length y may be basically defined to includeall possible DL centric/DL only/UL centric/UL only structures in the 5GNR communication system.

FIG. 4 is a diagram illustrating DL centric/DL only/UL centric/UL onlystructures as supportable slot structures in a 5G NR system according toan embodiment of the disclosure.

Referring to FIGS. 4, 410, 420, 430, and 440 denote slot structuressupportable in the 5GNR system, and the respective DL centric/DL only/ULcentric/UL only structures are illustrated. In 410 and 430, a guardperiod (GP) is a time required during DL-UL conversion, and the requiredlength may differ in accordance with a cell coverage or propagationdelay. Further, according to 3GPP RAN1#88bis agreement, the slot of the5G NR communication system is defined as follows.

-   -   Specification supports data channel having minimum duration of 1        OFDM symbol of the data and starting at any OFDM symbol to        below-6 GHz, in addition to above-6 GHz    -   Note: This may not be applied to all type of UEs and/or        use-cases    -   UE is not expected to blindly detect the presence of DMRS or        PT-RS    -   FFS: Whether a 1 symbol data puncturing can be indicated by        preemption indication

According to the agreement, the slot length of the 5G NR communicationsystem may correspond to 1 to 14 OFDM symbols. Since various slotstructures are supported in the 5G wireless communication as describedabove, a detailed operation method for this is necessary. For example,in case of y=14, the slot is defined by a basic slot, and may be definedas a slot structure supportable to all UEs. Further, in case of y thatis smaller than 14, the slot is defined by a mini slot, and may bedefined as a slot structure used for a specific use case, such asultra-reliable low latency communications (URLLC).

Further, in the 5G wireless communication, front-loaded DMRS has beenconsidered as a method for minimizing latency by shortening timerequired for data demodulation through fast channel estimation. Morespecifically, according to 3GPP RAN1#88 agreement, the front-loaded DMRSof the 5G NR communication system is defined as follows.

-   -   Front-loaded DMRS is mapped over 1 or 2 adjacent OFDM symbols    -   NR aims for performance at least comparable to DM-RS of LTE in        scenarios where applicable for both LTE and NR

Further, according to 3GPP RAN1#88bis agreement, the front-loaded DMRSof the 5G NR communication system may be defined as follows.

-   -   At least for slot, the position of front-loaded DL DMRS is fixed        regardless of the first symbol position of PDSCH    -   FFS: Mini-slot case

According to the agreement, the front-loaded DMRS is composed of one ortwo adjacent OFDM symbols, and in the basic slot structure, the positionof the front-loaded DMRS is fixed regardless of the start position ofthe PDSCH. However, in the mini slot, it is not determined whether theposition of the front-loaded DMRS is fixedly configured or isdynamically changed. According to 3GPP RAN1 discussions for the currentNR system, it is noted that accurate definition of the slot has not beenmade. Accordingly, wordings of the basic slot and the mini slot may notbe separately defined. However, based on the agreement below,explanation may be made on the assumption that a case corresponding tothat described below is called the basic slot, and a case notcorresponding to that described below is called a slot that is not thebasic slot.

-   -   For SCS of up to 60 kHz with NCP, y=7 and 14    -   FFS: whether/which to down select for certain SCS(s)    -   For SCS of higher than 60 kHz with NCP, y=14

Based on the above-described assumption, the basic slot may be used asthe basic structure that can be supported by all UEs. If the position ofthe DMRS is dynamically changed in consideration of a synchronizednetwork, it becomes difficult to manage DMRS interference. According tothe current agreement, the position of the front-loaded DMRS is fixedregardless of the start position of the PDSCH. If the position of thefront-loaded DMRS is fixed, the DMRS cannot be positioned on a frontside in spite of a short PDCCH region, and thus it is inefficient forthe purpose of minimization of the latency. However, in case of anon-basic slot, it has a slot structure used in a specific use case, andin consideration of the synchronized network, it is not greatlymotivated to fixedly configure the position of the DMRS regardless ofthe start position of the PDSCH. On the contrary, it may be ratheradvantageous to shorten the time required for data demodulation throughchannel estimation by positioning the front-loaded DMRS maximally on thefront side. Accordingly, the disclosure provides a method foreffectively configuring a DMRS position with respect to various slotstructures supported in the 5G wireless communication system.

Hereinafter, an embodiment of the disclosure will be described in detailwith reference to the accompanying drawings. Although an embodiment ofthe disclosure is described in a state where an LTE or LTE-A system isexemplified, it is also possible to apply the embodiment of thedisclosure even to other communication systems having similar technicalbackgrounds or channel types. For example, the 5th generation mobilecommunication technologies (5G and NR) that are developed after theLTE-A may be included therein. More specifically, the basic structure ofthe time-frequency domain in which signals are transmitted on the DL andUL may differ from those illustrated in FIGS. 1 and 2. Further,different kinds of signals may be transmitted on the DL and UL.Accordingly, the embodiment of the disclosure may also be applied toother communication systems through partial modifications thereof in arange that does not greatly deviate from the scope of the disclosure bythe judgment of those skilled in the art.

Further, in describing the disclosure, a detailed description of relatedfunctions or configurations will be omitted if it is determined that itobscures the subject matter of the disclosure in unnecessary detail.Further, all terms to be described later are terms defined inconsideration of functions of the disclosure, and may differ dependingon intentions of a user or an operator or customs. Accordingly, theyshould be defined on the basis of the contents of the whole descriptionof the disclosure. Hereinafter, the BS is the subject that performsresource allocation to the terminal, and may be at least one of an eNB,Node B, BS, radio connection unit, BS controller, and node on a network.The terminal may include UE, MS, cellular phone, smart phone, computer,or a multimedia system capable of performing a communication function.In the disclosure, a DL is a radio transmission path of a signal that istransmitted from the BS to the terminal, and an UL means a radiotransmission path of a signal that is transmitted from the terminal tothe BS.

Hereinafter, the DMRS to be described is a reference signal that istransmitted through UE-specific precoding and has a feature that the UEcan demodulate the signal even without additionally receiving precodinginformation, and uses the same name as that used in the LTE system.However, the term “DMRS” may be expressed by another term in accordancewith the user's intention and the use purpose of the reference signal.For example, it may be expressed by another term, such as UE-specific RSor dedicated RS. More specifically, the term “DMRS” is presented merelyas a specific example for easy explanation of the technical contents ofthe disclosure and to help understanding of the disclosure, and it isapparent to those of ordinary skill in the art to which the disclosurepertains that the above-described operation can be embodied throughother terms based on the technical concept of the disclosure.

In a first embodiment of the disclosure to be described hereinafter, amethod for determining a DMRS position in a basic slot structure inwhich only DL or UL exists will be described. In a second embodiment, amethod for determining a DMRS position with respect to a basic slotstructure in which only DL or UL exists will be described. In a thirdembodiment, a method for determining a DMRS position with respect to anon-basic slot structure in which only DL or UL exists will bedescribed. In a fourth embodiment, a method for determining a DMRSposition with respect to a basic slot structure in which DL and UL existat the same time will be described.

First Embodiment

In a first embodiment, a method for determining a DMRS position in abasic slot structure in which only DL or UL exists will be described. Asdescribed above, according to 3GPP RAN1 discussions for the current NRsystem, accurate definition of a slot has not been made. In the firstembodiment, the following case is defined as a basic slot based on 3GPPRAN1#86bis agreement.

-   -   For SCS of up to 60 kHz with NCP, y=7 and 14    -   FFS: whether/which to down select for certain SCS(s)    -   For SCS of higher than 60 kHz with NCP, y=14

Accordingly, with respect to a case where a subcarrier interval is equalto or smaller than 60 kHz, the length of a basic slot may be configuredas y=7 or y=14. Further, with respect to a case where the subcarrierinterval is larger than 60 kHz, the length of the basic slot may beconfigured as y=14. Accordingly, in the first embodiment, a method fordetermining a DMRS position for the basic slot structure with respect toa subframe in which only DL exists through the definition of the slotstructure is provided. First, with respect to the subframe in which onlyDL exists, the DMRS position in the basic slot structure may bedetermined by an area occupied by a control channel region. A controlformat indicator (CFI) serves to indicate how many OFDM symbols acontrol channel is composed of. In the 5G communication system, the CFImay be configured in the following method.

-   -   Alt-1: radio resource control (RRC) configuration    -   Alt-2: configuration by group common downlink control        information (DCI)

The Alt-1 is a method for semi-statically configuring CFI information,and Alt-2 is a method for dynamically configuring CFI informationsimilarly to the LTE system. In the 5G communication system, it ispossible to configure the CFI information in the above-described method.Further, the DMRS position in the basic slot structure with respect to asubframe in which only DL exists through the configured CFI may beconfigured as follows.Max(CFI)+1  Equation 1

The method for configuring the DMRS position according to Equation 1 hasa feature that the DMRS position is fixed regardless of the startposition of the PDSCH. In the 5G communication system, a plurality ofDMRS structures can be configured. As an example for this, aconfigurable DMRS structure may be divided into a front-loaded DMRS andan extended/additional DMRS. Specifically, the front-loaded DMRS is aDMRS that is positioned on the front side of an NR-PDSCH for fast datadecoding, and may be composed of one or two adjacent OFDM symbols.Accordingly, Equation 1 may indicate the position of the front-loadedDMRS.

FIG. 5 is a diagram illustrating a position of front-load DMRS if a slotlength corresponds to 7 or 14 OFDM symbols according to an embodiment ofthe disclosure.

Here, the position configuration of the front-loaded DMRS may bedetermined by the control channel region. If the CFI is 2 at maximum,the front-loaded DMRS is positioned at the third OFDM symbol as shown as510. If the CFI is 3 at maximum, the front-loaded DMRS is positioned atthe fourth OFDM symbol as illustrated as 520. If the position of thefront-loaded DMRS is determined by the control channel region that canbe maximally configured, there may be a loss in reducing the decodinglatency due to the DMRS position that is always configured at a fixedposition in case where a part or the whole of the control channel is notconfigured. Accordingly, in the disclosure, as an extended method, amethod capable of configuring the position of another front-loaded DMRSis provided. For example, if the CFI is 2 at maximum, an option forfixing the front-loaded DMRS to the first OFDM symbol as illustrated as530 may be configured in addition to the configuration for fixing thefront-loaded DMRS to the third OFDM symbol as illustrated as 510.Further, according to circumstances, if the two options are configured,the drawback that the position of the front-loaded DMRS is fixed can beremedied. Specifically, there may be various methods for configuring theposition of one or more front-loaded DMRSs. For example, a method forsemi-statically configuring the position of the front-loaded DMRSthrough an upper layer signaling such as an RRC may be considered. Asanother method, the position of the front-loaded DMRS may be configuredin system information such as master information block (MIB) or systeminformation block (SIB). Further, a method for dynamically configuringthe position of the front-loaded DMRS through a medium access control(MAC) control element (CE) or DCI. Unlike this, it is also possible toconfigure the position of the front-loaded DMRS through semi-persistentscheduling (SPS).

Next, an extended/additional DMRS will be described. According to thefront-loaded DMRS as described above, it is not possible to track a fasttime-varying channel in a high Doppler situation, and it is difficult toaccurately estimate the channel. Further, it is not possible to performcorrection of a frequency offset only with the front-loaded DMRS. Forthis reason, it is necessary to transmit an additional DMRS at the rearof the position where the front-loaded DMRS is transmitted in a slot.

FIGS. 6A, 6B, and 6C are diagrams illustrating a position where oneadditional extended/additional DMRS is transmitted in case of 14 OFDMsymbols according to various embodiments of the disclosure.

First, each position in which one additional extended/additional DMRS istransmitted is illustrated through 610, 620, 630, and 640 of FIGS. 6A,6B, and 6C in case of 14 OFDM symbols. Referring to FIGS. 6A to 6C, itis considered that maximally 2 DL control regions as 510 in FIG. 5 areconfigured, and OFDM symbol positions 12 and 13 are excluded fromcandidates considering that they can be used for GP and UL in a slotstructure in which DL and UL exist at the same time. Further, throughexperiments, throughput performance for 610 to 640 is illustrated as650. As the result of the experiments, it can be observed that theperformance is improved as one additional extended/additional DMRS issubsequently transmitted. Based on this, if one extended/additional DMRSis added, it may be a good alternative of 640 on the side of thethroughput performance. However, as the DMRS is positioned in the rear,the time required for data demodulation is shortened through fastchannel estimation, and this may cause a drawback on the side of thelatency minimization. Accordingly, in consideration of the throughputperformance and the latency based on the result of the experiments, thefollowing selection may be considered.

-   -   Alt-1: 610—latency is preferentially considered    -   Alt-2: 640—Throughput is preferentially considered    -   Alt-3: 620—Tradeoff between throughput and latency is        considered.

In case of Alt-3, if the structure of 620 is selected through 660,relative throughput is reduced to 103% or less as compared with 640, andthe position is configured to avoid the position in which CRS istransmitted in an LTE system. Accordingly, in the LTE-NR coexistencesituation, it has the advantage against the interference influence.Further, Alt-3 may be a good alternative in configuring the DMRSposition that is not different from the slot structure considered in asecond embodiment below. If the slot length corresponds to 14 OFDMsymbols, two or more extended/additional DMRS positions are necessaryaccording to the Doppler situation. For example, in a fast channelchanging environment in a state where the subcarrier spacing is 15 kHz,it is necessary to configure 4 extended/additional DMRS positions suchas 670. The DMRS position of 670 corresponds to a structure in which twolast symbols are emptied in consideration of the slot structure in whichDL and UL exist at the same time and the DMRS is positioned maximallysymmetrically. In all embodiments of the disclosure, temporal positionsin which DMRSs are configured based on one OFDM symbol are illustrated.For example, it is to be noted that DMRS transmitting positions can beadditionally configured if two adjacent OFDM symbols are necessary forantenna port extension. Further, in the disclosure, DMRS patternsapplied to temporal positions for sending the DMRSs are not limited. Inthe disclosure, the temporal positions for the DMRS sending are focused,but the applied DMRS patterns are not limited. For example, in anembodiment of the disclosure, all or partial REs of the DMRS sendingsymbols may be used as the DMRSs.

FIGS. 7A, 7B, and 7C are diagrams illustrating a DMRS pattern accordingto various embodiments of the disclosure.

For example, DMRS patterns of FIGS. 7A to 7C may be used. In addition,in case of the extended/additional DMRSs, a plurality of DMRSs aretemporally configured, and thus DMRS overhead problems may occur. Inthis case, it is possible to reduce the DMRS overhead by configuring theDMRS having low density on frequency. For example, in case of 720 ofFIGS. 7A to 7C, more effective transmission can be performed byconfiguring the DMRSs having low density on frequency in considerationof high DMRS density that 710 has. More specifically, the throughputperformance and relative gain are illustrated in 740 and 750 withrespect to methods 720 and 730 for configuring DMRSs having low densityon frequency. As the result of experiments, in case of configuring theextended/additional DMRSs, it can be observed that configuration of thefront-loaded DMRS and the extended/additional DMRS at the same lowdensity on frequency as 720 shows a better performance than theperformance of the configuration of them at different densities onfrequency as 730. Accordingly, the extended/additional DMRS may beconfigured to have the same density as that of the front-loaded DMRS.However, in consideration of MU-MIMO for a high-speed terminal and alow-speed terminal, the disclosure may use the following DMRSconfiguration method.

-   -   The UE may assume the density for additional DMRS is same for        number of transmission layers less than equal to X and reduced        otherwise.

In the method as described above, X denotes a parameter determining theDMRS density on frequency of the front-loaded DMRS and theextended/additional DMRS, and may be configured as the transmissionlayer number of 2 or 4. The above-described method is a method to enablea low-speed terminal to perform high-rank transmission, and asillustrated as 760 of FIGS. 7A to 7C, in accordance with X, thefront-loaded DMRS and the extended/additional DMRS may be configured atdifferent DMRS densities on frequency.

Although the DMRS position has been provided around DL, it is possibleto configure the DMRS in the same position with respect to UL in orderfor DL and UL to support a common DMRS structure. If the DL and UL havethe common DMRS structure, it may be easy to control interferencethrough orthogonal DMRS port allocation between UL and DL in anenvironment such as a dynamic TDD.

Hereinafter, a method by a BS for configuring a DMRS structure inconsideration of a point that the DMRS structure becomes diversifiedaccording to the disclosure will be described. It is to be noted thatthe following method for configuring a DMRS structure can be applied toother embodiments.

TABLE 2 dd-- ASN1START DMRS-timeDensityId ::= INTEGER (0..maxDMRS-TimeDMRS-frequencyDensityId ::= INTEGER (0..maxDMRS-Freqeuncy) -- ASN1STOP

Specifically, it is possible to indicate a temporally extended RSstructure through DMRS-timeDensityId in table 2. Here, maxDMRS-Timedenotes the number of maximally configurable DMRS-timeDensitylds. Forexample, it may be used to configure a temporally extended RS structure,such as a front-loaded RS and an extended/additional DMRS. Last, intable 2, different RS densities on frequency can be configured throughthe DMRS-frequencyDensityld. Here, maxDMRS-Frequency denotes themaximally configurable number of DMRS-frequencyDensityIds. For example,it may be used to configure a low RS density on frequency in order toadjust RS overhead. It is to be noted that the term for configured fieldvalues in table 2 can be replaced by another term. The terms used hereinare only for the purpose of presenting specific examples to facilitateexplanation of the technical contents of the disclosure and to helpunderstanding of the disclosure, but are not intended for limiting thescope of the disclosure. That is, it is apparent to those of ordinaryskill in the art to which the disclosure belongs that theabove-described operations can be embodied through other terms based onthe technical idea of the disclosure. More specifically, through theabove-described method, the DMRS structure can be semi-staticallyconfigured through RRC, and a terminal can grasp the structure of thecurrently transmitted DMRS through the value configured in the RRC.Next, a method by a BS for dynamically configuring a DMRS structuresuitable to a transmission environment will be described. If the DMRSinformation is configured in a MAC CE in a similar method to the methodfor configuring the DMRS information in the RRC, it is possible toconfigure the information on the DMRS structure more dynamically. Next,the simplest method for dynamically configuring the DMRS structure is toput the information on the DMRS structure in the DCI to be transmitted.In this case, for a basic operation, a DCI format to which a field fordynamically operating the DMRS structure is not applied may beseparately defined. If the DMRS structure is configured using the DCI,it becomes possible to dynamically change the DMRS structure. Incontrast, a DCI overhead may occur during the operation of the DMRSstructure. Since it may not be necessary to change the different DMRSpatterns on time and frequency as fast as dynamic signaling is necessaryto cope with the time-frequency channel change as in table 2, it may bemore preferable to configure the DMRS structure in the RRC.

Second Embodiment

In a second embodiment, a method for determining a DMRS position in abasic slot structure in which only DL or UL exists will be described. Inthe first embodiment, it is assumed that a terminal is configured as anormal CP, whereas in the second embodiment, it is assumed that theterminal is configured as an extended CP (ECP). If the terminal isconfigured as the extended CP, the following case is defined as a basicslot based on 3GPP RAN1#88bis agreement.

-   -   For 60 kHz ECP in the case with WA will be confirmed    -   One slot consists of 6 or 12 OFDM symbols    -   If down selection of NCP will be appeared between 7 or 14 OFDM        symbols, RAN1 will also apply the down selection of ECP between        6 or 12 OFDM symbols

Accordingly, if a subcarrier interval is 60 kHz, the length of a basicslot with respect to the ECP may be configured as y=6 or y=12.Accordingly, in the second embodiment, if the terminal is configured asthe extended CP through definition of the slot structure, a method fordetermining a DMRS position with respect to the structure of a basicslot in which only DL or UL exists is provided. In the same manner asthe method provided in the first embodiment, the position of thefront-loaded DMRS may be determined from Equation 1 through theconfigured CFI. Further, by additionally configuring the positions ofone or more front-loaded DMRSs, the drawback that the position of thefront-loaded DMRS is always fixed and a loss may occur in reducing thedecoding latency can be remedied.

FIG. 8 is a diagram illustrating a position of front-loaded DMRS if alength of a basic slot is configured to y=6 or y=12 with respect to anECP in case where a subcarrier interval is 60 kHz according to anembodiment of the disclosure.

Referring to FIG. 8, if the length of the basic slot is configured asy=6 or y=12 in a state where the subcarrier interval is 60 kHz, thepositions of the front-loaded DMRSs by Equation 1 are illustrated as 810and 820 of FIG. 8, and configuration of the position of the additionalfront-loaded DMRS is illustrated as 830. Further, in the same manner asthe first embodiment, it is not possible to track the fast time-varyingchannel in the high Doppler situation. Accordingly, it is difficult toaccurately estimate the channel. Further, it is not possible to performcorrection of the frequency offset only with the front-loaded DMRS. Forthis reason, it is necessary to transmit an additional DMRS at the rearof the position where the front-loaded DMRS is transmitted in a slot. Ifthe subcarrier interval is 60 kHz, as compared with the case where thesubcarrier interval is 15 kHz, the OFDM symbol interval is reduced to ¼.Accordingly, two or more extended/additional DMRSs may not be necessaryto track the fast time-varying channel as in the first embodiment.Accordingly, in the same manner as the first embodiment, it isconsidered that maximally 2 DL control regions are configured, and thetwo last OFDM symbols positions 12 and 13 are excluded from candidatesconsidering that they can be used for GP and UL in the slot structure inwhich DL and UL exist at the same time. Based on this, the followingselection may be considered.

-   -   Alt-1: 910—latency is preferentially considered    -   Alt-2: 920—Throughput is preferentially considered

Based on the result of experiments of the first embodiment, Alt-1 may bethe position in which the latency is preferential, and Alt-2 may be theposition in which the throughput is preferential.

Although the DMRS position has been provided around DL, it is possibleto configure the DMRS in the same position even with respect to UL inorder for DL and UL to support a common DMRS structure. If the DL and ULhave the common DMRS structure, it may be easy to control interferencethrough orthogonal DMRS port allocation between UL and DL in anenvironment such as a dynamic TDD.

Third Embodiment

In a third embodiment, a method for determining a DMRS position in abasic slot structure in which only DL or UL exists will be described.According to 3GPP RAN1 discussions for the current NR system, it is tobe noted that accurate definition of a slot has not been made.Accordingly, terms of a basic slot and a mini slot currently discussedin 3GPP RAN1 may not be separately defined. In the first embodiment, thefollowing case is defined as a basic slot based on 3GPP RAN1#86bisagreement.

-   -   For SCS of up to 60 kHz with NCP, y=7 and 14    -   FFS: whether/which to down select for certain SCS(s)    -   For SCS of higher than 60 kHz with NCP, y=14

According to the third embodiment, with respect to a case where asubcarrier interval is equal to or smaller than 60 kHz, the length of abasic slot may be configured as y=7 or y=14. Unlike this, in case of anon-basic slot, it is possible to discriminate the slot in the followingmethod. In an NR system, the non-basic slot may be called a mini slot.

-   -   Alt-1: Discriminated by a symbol length    -   Alt-2: Discriminated by a PDCCH monitoring period

Specifically, according to Alt-1, if the length of the basic slot isconfigured as y=7 with respect to a case where the subcarrier intervalis equal to or smaller than 60 kHz, a case where the length of the basicslot is configured to be smaller than y=7 may be defined as thenon-basic slot. Unlike this, if the length of the basic slot isconfigured as y=14, a case where the length of the basic slot isconfigured to be smaller than y=14 may be defined as the non-basic slot.Further, if the length of the slot is configured to be smaller than y=14with respect to a case where the subcarrier interval is larger than 60kHz, this case may be defined as the non-basic slot. Unlike this,according to Alt-2, the non-basic slot can be discriminated by a PDCCHmonitoring period. For example, if the PDCCH monitoring period isconfigured to X in case of the basic slot, a case where the slot havingthe PDCCH monitoring period that is smaller than X may be defined as thenon-basic slot. More specifically, if the slot is composed of one OFDMsymbol, the PDCCH monitoring may be performed for each OFDM symbol.

As described above, in the third embodiment, a method for determining aDMRS position for the non-basic slot with respect to a subframe in whichonly DL exists through the definition of the slot structure is provided.In case of the basic slot, it may be used as the basic structuresupported by all UEs. If the position of the DMRS is dynamically changedin consideration of a synchronized network, it becomes difficult tomanage DMRS interference. However, if the position of the front-loadedDMRS is fixed, the DMRS cannot be positioned on a front side in spite ofa short PDCCH region, and thus it is inefficient for the purpose ofminimization of the latency. However, in case of a non-basic slot, suchas a mini slot, it has a slot structure used in a specific use case, andin consideration of the synchronized network, it is not greatlymotivated to fixedly configure the position of the DMRS regardless ofthe start position of the PDSCH. It may be rather advantageous toshorten the time required for data demodulation through channelestimation by positioning the front-loaded DMRS maximally on the frontside. Accordingly, in consideration of this, the disclosure provides amethod for configuring a DMRS position for a non-basic slot with respectto a subframe in which only DL exists as follows.

-   -   Alt-1: The DMRS position is determined by a data starting        position indicator.    -   Alt-2: The DMRS position is determined by TCFI and slot symbol        duration.

FIG. 9 is a diagram illustrating a position of a DMRS according to anembodiment of the disclosure.

Of the disclosed methods, Alt-1 is a method for configuring a DMRSposition by a data starting position indicator newly defined in a 5G NRcommunication system, and is a method for determining that thefront-loaded DMRS is positioned in a data starting position indicated bythe data starting position indicator. In the 5G NR communication system,the data starting position indicator may be dynamically configured ormay be semi-statically configured.

FIG. 10 is a diagram explaining a method for configuring a DMRS positionby a data starting position indicator according to an embodiment of thedisclosure.

More specifically, the Alt-1 method will be described in detail throughFIG. 10. An example of a slot structure composed of 3 OFDM symbols isillustrated in FIG. 10, and DMRS, data, and control channel areillustrated with different colors. If a plurality of data startingposition indicators can be configured in the 5G NR communication system,it is also possible to configure the position of the front-loaded DMRSas 1010 of FIG. 10. Since the plurality of data starting positionindicators are supported, data transmission is possible from theforemost OFDM symbol in case where a control region does not exist in aspecific RB, and it is possible to locate the front-loaded DMRS therein.Unlike this, if only one data starting position indicator can beconfigured in the 5G NR communication system, it is possible toconfigure the position of the front-loaded DMRS as 1020. In this case,as illustrated as 1020, if there is not a control region in a specificRB, data transmission from the foremost OFDM symbol becomes impossible,and the position of the front-loaded DMRS may be configured at a datastart position indicated by one data starting position indicator. Inaccordance with the method for configuring the data starting positionindicator of Alt-1, the position of the front-loaded DMRS may bedynamically or semi-statically configured. Unlike this, Alt-2 is amethod for determining a DMRS position by CFI and slot symbol duration.More specifically, the position of the front-loaded DMRS may bedetermined through the following equation.Min(Max(CFI)+1,slot duration)  Equation 2

In Equation 2, the position of the front-loaded DMRS is determined bythe CFI and the slot symbol duration. In Equation 2, the slot durationis a value configured in case where the slot length is smaller than max(CFI). For example, if the slot is composed of one symbol, thefront-loaded DMRS is positioned at the first OFDM symbol regardless ofthe CFI. Equation 2 may be divided into two different methods accordingto the CFI value. The first method is a method for determining the CFIvalue as a value configured by a control resource set (CORESET). In thiscase, it is not necessary to perform signaling of additional informationon the CFI value configured in the CORESET to the terminal.

FIG. 11 is a diagram explaining a method for configuring a DMRS positionby CFI and slot symbol durations according to an embodiment of thedisclosure.

More specifically, the Alt-2 method will be described in more detailthrough FIG. 11. An example of a slot structure composed of 3 OFDMsymbols is illustrated in FIG. 11, and DMRS, data, and control channelare illustrated with different colors. In case of the first method,since the position of the front-loaded DMRS is determined according tothe CFI configured in the CORESET, it is possible to configure the DMRSposition maximally next to a control channel. As illustrated as 1110 and1120 of FIG. 11, 1110 illustrates a DMRS configuration positionaccording to the first method in case where the CFI value configured inthe CORESET is 2, and 1120 illustrates a DMRS configuration position incase where the CFI value configured in the CORESET is 1. If the DMRS canbe positioned further on the front side through signaling of PDSCH startposition information or additional configuration, as illustrated as 1130and 1140, the DMRS position is configured further on the front side tofurther minimize the latency. In this case, the DMRS position may bedetermined by granularity for the data starting position on thefrequency axis. For example, through configuration of the DMRS positionin the unit of a resource block group (RBG), multiple RBGs, a bandwidthpart (subband), or a PRB level, it is possible to more effectivelyoperate the data scheduling and DMRS channel estimation. The secondmethod using Equation 2 is determined in consideration of allconfigurable values for the CFI value. In case of using this method, theposition of the front-loaded DMRS may be fixed regardless of the startposition of the PDSCH even with respect to the non-basic slot. Forexample, as illustrated as 1150 and 1160, in case where the CFI value ofthe 1150 region is 2 and the CFI value of the 1120 region is 1, theposition of the front-loaded DMRS may be determined as the third OFDMsymbol in consideration of the max value of the two values. In case ofthe disclosed Alt-2, the DMRS position is determined by the max value ofthe CFI, and thus the frequency of the DMRS position change may besmall. As described above in the first embodiment, if the CFIinformation is semi-statically configured, the frequency of the DMRSposition change may become smaller.

Although the DMRS position has been provided around DL, it is possibleto configure the DMRS in the same position even with respect to UL inorder for DL and UL to support a common DMRS structure. If the DL and ULhave the common DMRS structure, it may be easy to control interferencethrough orthogonal DMRS port allocation between UL and DL in anenvironment such as a dynamic TDD.

Fourth Embodiment

In a fourth embodiment, a method for determining a DMRS position in abasic slot structure in which DL and UL exist at the same time will bedescribed. In the first embodiment, the following case is defined as abasic slot based on 3GPP RAN1#86bis agreement.

-   -   For SCS of up to 60 kHz with NCP, y=7 and 14    -   FFS: whether/which to down select for certain SCS(s)    -   For SCS of higher than 60 kHz with NCP, y=14

According to the first embodiment, with respect to a case where asubcarrier interval is equal to or smaller than 60 kHz, the length of abasic slot may be configured as y=7 or y=14. Further, with respect to acase where the subcarrier interval is larger than 60 kHz, the length ofthe basic slot may be configured as y=14. According to the agreement,the slot length y may be defined to include all of DL centric/DL only/ULcentric/UL only structures basically possible in the 5G NR communicationsystem. Accordingly, in the DL centric or UL centric structure in whichDL and UL exist at the same time, due to the DL/UL symbol length and GPinfluence, the DMRS position may be configured differently from the DLonly or UL only structure. For the same reason, in the fourthembodiment, a method for determining a DMRS position with respect to abasic slot structure in which DL and UL exist at the same time isprovided.

FIG. 12 is a diagram illustrating a basic slot structure in which DL andUL exist at the same time, according to an embodiment of the disclosure.

More specifically, FIG. 12 illustrates a basic slot structure 1210 inwhich DL and UL exist at the same time. Referring to FIG. 12, DL, GP,and UL are illustrated with different colors. In this case, the positionof the front-loaded DMRS may be configured in the same method as themethod of Equation 1 according to the first embodiment, or may beconfigured through Equation 2 according to the third embodiment. In thefirst, second, and third embodiments, it is possible to configure the ULDMRS position in the same position as the position of the DL DMRSposition on the assumption of the DL only or UL only structure. However,in the DL centric or UL centric structure in which DL and UL exist atthe same time, regions occupied by DL/GP/UL may differ from each other,and thus such configuration may be difficult. Accordingly, it isproposed to determine the position of the front-loaded DMRS for UL basedon the GP as in the following equation.The last symbol position for GP+1  Equation 3

According to Equation 3, “the last symbol position for GP” in FIG. 12becomes 8, and the position of the front-loaded DMRS for UL may startfrom 9.

In order to perform the above-described embodiments of the disclosure, atransmitter, a receiver, and a processor of a terminal or a BS areillustrated in FIGS. 13 and 14. According to the first to fourthembodiments, a method for configuring a DMRS position and atransmission/reception method between a BS and a terminal are described,and for this, the receiver, the processor, and the transmitter of the BSor the terminal should operate according to the respective embodiments.

FIG. 13 is a block diagram illustrating an internal structure of aterminal according to an embodiment of the disclosure.

Referring to FIG. 13, a terminal according to the disclosure may includea terminal receiver 1300, a terminal transmitter 1304, and a terminalprocessor 1302. In an embodiment of the disclosure, the terminalreceiver 1300 and the terminal transmitter 1304 may be commonly called atransceiver. The transceiver may transmit/receive a signal with a BS.The signal may include control information and data. For this, thetransceiver may be composed of an RF transmitter for up-converting andamplifying the frequency of a transmitted signal, and an RF receiver forlow-noise-amplifying and down-converting the frequency of a receivedsignal. Further, the transceiver may receive a signal through a radiochannel, and may output the received signal to the terminal processor1302. The transceiver may also transmit the signal that is output fromthe terminal processor 1302 through the radio channel. The terminalprocessor 1302 may control a series of processes for the terminaloperation according to the above-described embodiment of the disclosure.For example, the terminal receiver 1300 may receive a reference signalfrom the BS, and the terminal processor 1302 may control to analyze amethod for applying the reference signal. Further, the terminaltransmitter 1304 may also transmit the reference signal.

FIG. 14 is a block diagram illustrating an internal structure of a BSaccording to an embodiment of the disclosure.

Referring to FIG. 14, a BS according to an embodiment of the disclosuremay include a BS receiver 1401, a BS transmitter 1405, and a BSprocessor 1403. In an embodiment of the disclosure, the BS receiver 1401and the BS transmitter 1405 may be commonly called a transceiver. Thetransceiver may transmit/receive a signal with a terminal. The signalmay include control information and data. For this, the transceiver maybe composed of an RF transmitter for up-converting and amplifying thefrequency of a transmitted signal, and an RF receiver forlow-noise-amplifying and down-converting the frequency of a receivedsignal. Further, the transceiver may receive a signal through a radiochannel, and may output the received signal to the BS processor 1403.The transceiver may also transmit the signal that is output from the BSprocessor 1403 through the radio channel. The BS processor 1403 maycontrol a series of processes for the BS operation according to theabove-described embodiment. For example, the BS processor 1403 maycontrol to determine the structure of a reference signal and to generateconfiguration information of the reference signal to be transferred tothe terminal. Thereafter, the BS transmitter 1405 may transfer thereference signal and the configuration information to the terminal, andthe BS receiver 1401 may also receive the reference signal.

Further, according to an embodiment of the disclosure, the BS processor1403 may process DMRS position configuration. Further, the BStransmitter 1405 may transfer information required for this to theterminal.

While the disclosure has been shown and described with reference tovarious embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the disclosure as definedby the appended claims and their equivalents.

What is claimed is:
 1. A method by a terminal in a wirelesscommunication system, the method comprising: identifying a mapping typefor a physical downlink shared channel (PDSCH) of a terminal from afirst mapping type and a second slot mapping type; in case that themapping type is the first mapping type, determining that a demodulationreference signal (DMRS) is positioned on one symbol of a third symbol ora fourth symbol of a slot in a downlink based on a master informationblock (MIB) received on physical broadcast channel (PBCH); in case thatthe mapping type is the second mapping type, determining that the DMRSis positioned on a first symbol of a scheduled data resource; andreceiving the DMRS based on the determined position from a base station.2. The method of claim 1, wherein the determining that the DMRS ispositioned on the first symbol of the scheduled data resource furthercomprising: in case that the mapping type is the second mapping type andthe PDSCH allocation collides with resources reserved for a controlregion resource (CORESET), determining that the DMRS is positioned on afirst symbol after at least one symbol of the CORESET.
 3. The method ofclaim 1, further comprising: receiving information on an additional DMRSon a higher layer signaling; in case that one additional DMRS isconfigured by the higher layer signaling, determining that theadditional DMRS is positioned on a twelfth symbol of a slot for durationin 14 symbols; in case that three additional DMRSs are configured by thehigher layer signaling, determining that the additional DMRSs arepositioned on sixth symbol, ninth symbol and twelfth symbol of the slotfor duration in 14 symbols; and receiving the additional DMRS based onthe information on the additional DMRS, wherein the DMRS and theadditional DMRS are generated based on same parameters.
 4. The method ofclaim 1, further comprising: determining a position for a DMRS in anuplink, the position for the DMRS in the uplink corresponds to theposition for the DMRS in the downlink, in case that the mapping type isthe first stet-mapping type.
 5. A terminal in a wireless communicationsystem, the terminal comprising: a transceiver configured to transmitand receive a signal; and at least one processor configured to: identifya mapping type for a physical downlink shared channel (PDSCH) of aterminal from a first mapping type and a second mapping type, in casethat the mapping type is the first mapping type, determine that ademodulation reference signal (DMRS) is positioned on one symbol of athird symbol or a fourth symbol of a slot in a downlink based on amaster information block (MIB) received on physical broadcast channel(PBCH), in case that the mapping type is the second mapping type,determine that the DMRS is positioned on a first symbol of a scheduleddata resource, and control the transceiver to receive the DMRS based onthe determined position from a base station.
 6. The terminal of claim 5,wherein the least one processor further configured to in case that themapping type is the second mapping type and the PDSCH allocationcollides with resources reserved for a control region resource(CORESET), determine that the DMRS is positioned on a first symbol afterat least one symbol of the CORESET.
 7. The terminal of claim 5, whereinthe least one processor further configured to control the transceiver toreceive information on an additional DMRS on a higher layer signaling,in case that one additional DMRS is configured by the higher layersignaling, determine that the additional DMRS is positioned on a twelfthsymbol of a slot for duration in 14 symbols, in case that threeadditional DMRSs are configured by the higher layer signaling, determinethat the additional DMRSs are positioned on sixth symbol, ninth symboland twelfth symbol of the slot for duration in 14 symbols, and controlthe transceiver to receive the additional DMRS based on the informationon the additional DMRS, wherein the DMRS and the additional DMRS aregenerated based on same parameters.
 8. The terminal of claim 5, whereinthe least one processor further configured to determine a position for aDMRS in an uplink, the position for the DMRS in the uplink correspondsto the position for the DMRS in the downlink, in case that the mappingtype is the first mapping type.
 9. A method by a base station in awireless communication system, the method comprising: in case that amapping type for a physical downlink shared channel (PDSCH) is a firstmapping type, transmitting a demodulation reference signal (DMRS) on onesymbol of a third symbol or a fourth symbol of a slot in a downlink; andin case that the mapping type is a second mapping type, transmittingthat the DMRS on a first symbol of a scheduled data resource, whereinthe mapping type of the terminal is identified from the first mappingtype and the second mapping type and the position of the DMRS isdetermined based on the mapping type by the terminal, and wherein, incase that the mapping type is the first mapping type, a position of DMRSis determined, by the terminal, based on a master information block(MIB) signaling on physical broadcast channel (PBCH).
 10. The method ofclaim 9, wherein the transmitting that the DMRS on the first symbol ofthe scheduled data resource further comprising: in case that the mappingtype is the second mapping type and the PDSCH allocation collides withresources reserved for a control region resource (CORESET), transmittingthe DMRS on a first symbol after at least one symbol of the CORESET. 11.The method of claim 9, further comprising: transmitting information onan additional DMRS on a higher layer signaling; in case that oneadditional DMRS is configured by the higher layer signaling,transmitting the additional DMRS on a twelfth symbol of a slot forduration in 14 symbols; and in case that three additional DMRSs areconfigured by the higher layer signaling, transmitting the additionalDMRSs on sixth symbol, ninth symbol and twelfth symbol of the slot forduration in 14 symbols, wherein the DMRS and the additional DMRS aregenerated based on same parameters.
 12. The method of claim 9, furthercomprising: receiving a DMRS in an uplink from the terminal, wherein aposition for the received DMRS in the uplink is determined, the positionfor the DMRS in the uplink corresponds to the position for the DMRS inthe downlink, in case that the mapping type is the first mapping type.13. A base station in a wireless communication system, the base stationcomprising: a transceiver configured to transmit and receive a signal;and at least one processor configured to control the transceiver, incase that a mapping type for a physical downlink shared channel (PDSCH)is a first mapping type, to transmit a demodulation reference signal(DMRS) on one symbol of a third symbol or a fourth symbol of a slot in adownlink, and in case that the mapping type is a second mapping type, totransmit that the DMRS on a first symbol of a scheduled data resource,wherein the mapping type of a terminal is identified from the firstmapping type and the second mapping type and the position of the DMRS isdetermined based on the mapping type by the terminal, and wherein, incase that the mapping type is the first mapping type, a position of DMRSis determined, by the terminal, based on a master information block(MIB) signaling on physical broadcast channel (PBCH).
 14. The basestation of claim 13, wherein the at least one processor furtherconfigured to, in case that the mapping type is the second mapping typeand the PDSCH allocation collides with resources reserved for a controlregion resource (CORESET), to control the transceiver to transmit theDMRS on a first symbol after at least one symbol of the CORESET.
 15. Thebase station of claim 13, wherein the at least one processor furtherconfigured to control the transceiver to transmit information on anadditional DMRS on a higher layer signaling, in case that one additionalDMRS is configured by the higher layer signaling, transmit theadditional DMRS on a twelfth symbol of a slot for duration in 14symbols, and in case that three additional DMRSs are configured by thehigher layer signaling, transmit the additional DMRSs on sixth symbol,ninth symbol and twelfth symbol of the slot for duration in 14 symbols,wherein the DMRS and the additional DMRS are generated based on sameparameters.
 16. The base station of claim 13, wherein the at least oneprocessor further configured to control the transceiver to receive aDMRS in an uplink from the terminal, wherein a position for the receivedDMRS in the uplink is determined, the position for the DMRS in theuplink corresponds to the position for the DMRS in the downlink, in casethat the mapping type is the first mapping type.